According to GizmoBolt, the new software, build number 14.4.A.0.108 has already began rolling out to Xperia Z1 and Z Ultra handsets. Sony’s product page for each of the three Z series phones confirms the over-the-air (OTA) push to devices of Android 4.4.4.

Users in select regions who download and install the latest firmware update for their Xperia Z series phone will get an upgrade from the existing Android 4.4.2 KitKat release. Updates to Xperia Sony apps, optimizations and bug fixes are bundled in the update file. One commenter on XperiaBlog confirms fixes for some issues that Xperia Z series device owners running Android 4.4.2 may experience. Android 4.4.4 patches random reboots, battery drain, crackling sounds, overheating and bluetooth and wifi issues.

Along with system performance tweaks, Android 4.4.4 brings along changes to the user interface (UI) for an enhanced user experience. An official changelog details what’s new in the Android 4.4.4 update.

Xperia Z1 Compact, Z1 and Z Ultra device owners will notice: a new simple home launcher found on the Xperia Z2, the latest Xperia Home Launcher (version 6.2.1.A.0.11), Sony’s TV SideView app and an overall more stable UI. Sony’s statement about the Android 4.4.4 firmware update notes an improved camera experience.

The Android 4.4.4 software update for Xperia Z1 Compact, Xperia Z1 and Xperia Z Ultra also features security updates from Google. Improvements to Google native apps such as Google Voice, Contact, Music streaming and Google + are also included in this latest Android OS firmware release.